Field
The present invention relates to a method of controlling a flow rate of fluid, a mass flow rate control device (mass flow controller) for executing the method, and a mass flow rate control system (mass flow control system) utilizing the mass flow controller. For example, the present invention relates to a method of controlling a flow rate of fluid, which can appropriately be utilized for control of start and stop of supply of a process gas to a semiconductor manufacturing apparatus and control of a supply amount thereof, a mass flow controller for executing the method, and a mass flow rate control system utilizing the mass flow controller.
Background
The mass flow rate control device (mass flow controller) is widely used, for example, in order to control a flow rate of a process gas supplied to an inside of a chamber in a manufacturing process for a semiconductor. The mass flow controller is used not only solely, but also as a component for constructing a mass flow control system including a combination of a plurality of mass flow controllers and other components.
The mass flow controller generally includes a flow meter serving as means for measuring the flow rate, a flow control valve serving as means for controlling the flow rate, and a controlling section for controlling those means. A user opens the flow control valve to start supply of fluid (for example, process gas) when the fluid needs to be supplied, and closes the flow control valve to stop the supply of the fluid when the supply of the fluid becomes no longer necessary. Moreover, the flow rate of the fluid can be measured by the flow meter while the flow control valve is opened, and opening of the flow control valve can be controlled in accordance with the measured value of the flow rate.
In the manufacturing process for a semiconductor, semiconductor devices each having a fine and complex structure are manufactured by supplying various types of process gases to the inside of the chamber. It is desired to decrease a period from transmission of a signal from the controlling section to the flow control valve until actual start or stop of the supply of the fluid as much as possible in order to supply a required type of process gas in a required amount at a required time point. In order to satisfy this requirement, there are proposed various technologies for opening/closing the flow control valve of the mass flow controller at high speed without a delay.
For example, in WO 2013/115298 A1, there is disclosed an invention of a flow control device and a program for enabling high-speed flow rate response, which was proposed by the applicant of the present invention. With the invention disclosed in WO 2013/115298 A1, a period required for bringing the flow control valve from a closed state to an open state can be decreased by, for example, outputting a spike voltage signal from a drive circuit to a flow control valve.